Interpretation of digital partial discharge measurements

The presence of partial discharges is one of the most prominent indicators of defects and ongoing degradation processes in electrical insulation systems. On-line partial discharge measurements provide information about progressing degradation under operational stress or defects which are only excited by the operational stress (e.g. vibration of e.g. motors). Thus, a complementary insight in the state of the apparatus can be gained which is not accessible through off-line testing. Provided a “diagnostic connector” or sensor is integrated into or attached to the high voltage system, periodic measurements, trend recording or even on-line monitoring becomes possible. Digital partial discharge measurements with enhanced signal conditioning techniques allow better visualization and interpretation of data in terms of risk and defect type and provide better noise reduction and identification capabilities. They are not only applied to the R&D environment, but are today used in quality assurance and online situations. The interpretation of digital pd measurements not only includes the defect assessment (physics of partial discharge) but also an identification of noise sources and non-pd signals. These “interpretations” lead to a choice of sensors and signal processing techniques to be chosen from a so-called toolbox which serves to optimize the measurement procedures